Backflow prevention sink



FIG. 1 is a front perspective view of the backflow prevention sink.

FIG. 2 is a front view of the backflow prevention sink.

FIG. 3 is a bottom view of the backflow prevention sink; and,

FIG. 4 is a side view of the backflow prevention sink.

The present application is directed to the design illustrated in thedrawings. The broken line portions of the disclosure are forillustrative purposes only and form no part of the claimed design.

The ornamental design for a backflow prevention sink, as shown anddescribed.